In a glass sheet windshield forming operation such as that disclosed in U.S. patent application Ser. No. 527,344, a heated thin glass sheet is formed against an upwardly facing full face male glass sheet shaping mold. The glass sheet formed on the full face mold is subsequently picked up by vacuum for further processing. During the application of vacuum from above, the formed glass sheet often changes shape because of the plastic condition of the glass sheet. During the subsequent transfer to a glass sheet processing ring, the glass sheet tends to sag when the vacuum is released, but this sagging is insufficient to correct the upward deflection caused by the vacuum pick up.
U.S. Pat. No. 4,687,501 discloses the use of heat shields in connection with a glass sheet bending mold to control edge temperature of a glass sheet.
U.S. Pat. No. 4,297,188 discloses the movement of a glass sheet vacuum forming mold outside a furnace between successive bending operations to control the temperature rise of the mold.
U.S. Pat. No. 3,862,828 discloses controlling furnace roof temperature during glass sheet bending.
U.S. Pat. No. 3,600,150 discloses bending glass sheets between refrigerated bending forms to control temperature.